Commutator.



No. 696,488. Patented Apr. I, I902.

E. D. PRIEST & G. L. SCHERMERHDRN.

C O H M U T A T O B.

(Application filed Nov. 80, 1900.)

(N0 Model.)

Wtnesses; I Jnvent, ra

, EdwardDpm st,

Ge org e Llscher merhorn j tty.

UNITED STATES PATENT OFFICE.

EDWARD D. PRIEST AND GEORGE L. SOHERMERHORN, OF SOHENEOTADY, NEYV YORK, ASSIGNORS TO GENERAL ELECTRIC COMPANY, A CORPO- RATION OF NEXV YORK.

COMMUTATOR.

SPECIFICATION forming part of Letters Patent No. 696,488, dated April 1, 1902. Application filed November 80, 1900. Serial No. 38,242. (No model.)

To (Z7 whom it may concern:

Be it known that we, EDWARD D. PRIEST and Gnonen L. SOHERMERHORN, citizens of the United States, residing at Schenectady,

county of Schenectady, State of New York,

have invented certain new and useful Improvements in Oomn1utators,(Oase No.1,760,) of which the following is a specification.

Our invention relates to commutators such :0 as are commonly used on dynamo-electric machines.

It consists of an improved insulation for such devices by the use of which arcing and wear are materially reduced.

Commutators for dynamoelectric machines are usually constructed of alternate strips of copper and mica, the mica being used, as is well understood, toinsulate the copper strips or segments from each other. Mica is used because it is a good insulator and because it will endure the high temperatures at which commutators are necessarily run in practice, particularly in railway-motors. It is, however, as we have discovered, open to the serious objection that it is very hard and does not wear down and burn off like the copper segments, whereby it results that after the commutator has been working a reasonable time some or all of the mica strips tend to 36 project above the general level of the commutator and to cause the brushes to jump slightly many times each revolution. This persists until the mica strips rise so far above the level of the commutator that they are actually broken olt by the brushes, and the result is frequently that the commutators are or spark excessively during the operation of the machine.

Our improvement, broadly speaking, con- 40 sists in the substitution for the mica insulation generally employed of some softer heatresisting material-as, for example, asbestos. WVe find that commercial sheet-asbestos if out to the proper shape and usedin the mannfacture of commutators in place of the mica ordinarily employed will resist the temperatures at which commutators are run and will furnish good and reliable insulation; but as it sometimes happens that asbestos contains impuritiessuch, for example, as traces of iron-we further find it advantageous to use,

in addition to the asbestos, a thin strip of mica, preferably one on each side of the as bestos. These mica strips are so thin that they have no appreciable strength and are readily broken oil? by the brushes, so that they do not cause the objections above noted,while at the same time they tend to prevent the possibility of the existence of conductingpaths from segment to segment, which might 6o otherwise occur by reason of some impurity in the asbestos.

In the drawings attached to this specification, Figure 1 is an elevation, partly in section, of a commutator. Fig. 2 is across-section on the line 2' 2 of Fig. 1, and Fig. 3 is a detail on a large scale.

The particular commutator to which our invention is here shown as being applied is that set forth in the patent to W'. B.'Potter, No. 608,299, August 2, 1898; butit will readily be understood that our invention is capable of application to almost any existing type of commutator.

The commutator-segments A are mounted on a cast-metal shell 13, which shell is provided at one end with a conical flange 0, formed integral therewith, and at the other end with an adjustable clampingring D. The clamping-ring and flange are each provided with conical surfaces which engage corresponding surfaces on the segments and hold the latter in place. Between the conical surface of the clamp and the corresponding surfaces of the segments are layers of insulatin g material E,which insulate the segments from the supporting-shell. The clampingring D is held in place and adjusted by the nut G and is prevented from turning by the pin H, which enters a slot 1, formed therein. 0 The nut G is prevented from loosening by means of one or more screws J. The under side of each bar is provided with a lug K, having'angular or conical clamping-faces K, with which the conical flange 0 and the adjusting-ring D engage. The portion M of each segment is slotted at M to receive the armaturedcads N, and between the portion find it useful in practice to place-oneach i side of the asbestos strips F a'thin stripofi.

mica F F. In commutators for railway-mo tors constructed in accordance with our invention we have used asbestosstri-ps of a thick: ness of thirty millimeters and mica stripsrof. five millimeters, thickness, though in other commutatorsconstructed'in accordance with our, present invention we have entirelyomitted the micawith successful results. Wefind it unnecessary, as, before stated; to use the mica in certain cases,, andfthese cases would naturally be where the, potential difference between two adjacent bars-was, comparatively small as, for-example, fivevolts, We further find it1advantageous to fill .theasblestos with linseed-oil, varnish, or withsomeresinous substancewhich. will neutralize thenatu: ral hygroscopic tendency of the asbestos, it. will be evidentthat the presenceotmoisture in thecommutator would. be, objectionable.

By means of. our present inventionzwe have been enabledjto greatlyreducethesparking, on various commercial dynamo-electric mai chines and have in many caseslargelymeducedj. the rate at which-jthie. commutators T weardown and haveimprovedtheservice ofir the, co mm u tators in, a marked degree.

What we claim asnew, and'desireto secureby Letters Patent of the. United States,is,

of conducting and of heat-resistinginsulating material, the insulating material being of such anature that it wears or tends to wear as fast as, or faster than, the conducting material.

2. A commutator for-dynamo-electric machines, consisting of conducting-segments separated by soft; insulating material which will wear or crumble away at least as fast as the segments. 7 7' 3.- A 'commutator for dynamo-electric machines, composed of alternate strips of copper, and of asbestos which will wear or crumble away at least as-fast as the copper strips.

4. Acommutator; for dynamo-electric machines, consisting of conducting-segments separated by soft ins ulatingm aterial, and thin highly-insulating reinforcing 7 strips in .conjn c ion with; the. insulatingunaterial; 5. commutator or.dynamorelectric-mafchines, composed; of, conducting segments separated ,byfasbestos, withlone or morethin mica strips; reinforcing the, asbestos.v

6. A commutator for dynamo-electric mae chinescomppsedof,conducting;segn1ents,separated by asbestos, with,a thi n strip. of mica on each side of each strip of asbestos.

7. A-commutatorcomprisingalternatecon- 'ing of such nature .tlmtthey-will wear away at least as fast, as; theponductingmtri ps, and being; tr ated? with. a; water.- shdding, sub,- stance, In:- Witness. whereof i we have hereunto set EDWARD J). PRIEST. GEORGE I... SCHERMERHORN. Witnesses BENJAMIN B. HULL,..

MARGARET E. WooLLEY.

1 A commutator built up of alternateistrips Zducting, and insulalting. strips, the latter beourhands this 28th ,day.,o f Noyembe1311900. 

